Magnesium fluoride（MgF2） has good transparency in the wavelength range of 120-7000nm. In addition, it also has excellent mechanical and thermal shock performance, as well as a high laser damage threshold. This type of window usually has a wide transmission band, which can effectively transmit various types of light into the optical system. Magnesium fluoride is also a commonly used birefringent material, commonly used as the base material for achromatic and infrared waveplates.